JPS6020411B2 - Resin composition with excellent crushing properties and heat melting properties, and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel resin composition having both excellent pulverization properties and heat melting properties, and a method for producing the same.

Currently, low molecular weight polymers made by polymerizing one or more types of various polymerizable vinyl monomers to have a number average molecular weight of several thousand to several tens of thousands are suitable for crushability and heat meltability, so for example, It is used as a base resin for powder coatings and dry electrophotographic toners, and for these applications, the base resin is melt-blended with organic or inorganic substances as necessary, and the blend is finely ground. When used as a powder coating or toner, a process of heat-melting is used.

Therefore, two important characteristics are important for these base resins: crushability and heat meltability. However, although the low molecular weight resins used as base resins have the advantage of being easily pulverized, they are pulverized too much and become too powdery, making it difficult to obtain the required particle size. The disadvantage is that the yield obtained is very low. For example, it is appropriate to grind the particles to about 20 to 50 microns for powder coatings, and about 5 to 20 microns for dry electrophotographic toners, and it is also possible to adjust the particle size within a certain range. However, when a conventional base resin is pulverized by a ball mill or jet pulverization, the average particle size is approximately 5 to 30 microns, but it is not uncommon for the particle size distribution to range from less than 1 micron to several tens of microns. It also had the property of being easily pulverized. In powder coatings, excessively pulverized particles not only cause the paint to scatter easily, causing problems such as paint loss and environmental pollution, but also contribute to the loss of surface smoothness of the paint film. In addition, as toner for dry electrophotography, these fine particles not only float in the dry electrophotographic equipment and stain the copies and deteriorate the images, but also adhere to the optical equipment and damage the equipment. It is also one of the causes of shortening the lifespan of people. Regarding heat meltability, although conventional base resins exhibit good behavior at a certain temperature, they have the disadvantage that this behavior worsens with slight temperature changes. For example, in the case of powder coatings, even a slight drop in the temperature of the paint will reduce its thermal meltability and fluidity, resulting in poor adhesion and surface smoothness of the paint film; Even when the height was increased, the molten paint flowed too much, resulting in uneven thickness at the edges and sagging of the paint.
Furthermore, when using toner for dry electrophotography, if the temperature of the fixing section is only slightly lower than the set temperature, the adhesion of the toner to the paper will be poor and the image will easily separate from the paper, and if the temperature is slightly higher than the set temperature, the toner will not adhere well to the paper. The disadvantages are that the toner soaks into the paper and the toner flows too much, reducing the resolution and making the copied image shiny and difficult to see. In view of the above-mentioned drawbacks of low-molecular-weight resins conventionally used in powder coatings, etc., the present inventors have an object to provide a new resin composition with excellent crushing properties and heat-melting properties, and a method for producing the same. As a result of various studies aimed at this purpose, the present invention was achieved. That is, the gist of the present invention is a low polymerization degree polymer obtained mainly from one or more monomers selected from styrenes, acrylic esters, and methacrylic esters, and styrenes, acrylic esters, and methacrylic acid. The number average molecular weight obtained mainly from one or more monomers selected from esters is 100,000 to 100,000.
The number average molecular weight (Mn
) is 2,000 to 30,000, weight average molecular weight (Mw)
A resin composition with excellent crushing properties and heat melting properties, which has a number average molecular weight (Mn) of 3.5 to 40 and a glass transition temperature of 20 to 120°C, and styrenes, 10 parts by weight of a polymerizable monomer mainly composed of one or more monomers selected from acrylic esters and methacrylic esters, and one or more monomers selected from styrenes, acrylic esters, and methacrylic esters. By polymerizing a mixed solution containing 5 to 4 parts by weight of a high polymerization degree polymer having a number average molecular weight of 100,000 to 500,000, the low polymerization degree polymer and the high polymerization degree polymer are polymerized. The resin composition has a number average molecular weight (Mn) of 2,000 to 30,000, and a weight average molecular weight (Mw)/number average molecular weight (Mn) of 3.5. 40 and a glass transition temperature of 20 to 12,000.

Therefore, the resin composition of the present invention is a composition in which a low polymerization degree polymer and a high polymerization degree polymer are uniformly mixed, and the molecular weight of the high polymerization degree polymer and the composition is If measured, the former has a number average molecular weight (Mn) of 100,000~
500,000, and for the latter the number average molecular weight (
Mn) is 2,000 to 30,000, and the value obtained by dividing the weight average molecular weight (Mw) by Mn, that is, Mw/Mn
indicates a value of 3.5 to 4, preferably 4 to 20, and Mn and Mw in the present invention are measured by gel permeation chromatography (GPC) under the following conditions. is the value to be used.

That is, a solvent (tetrahydrofuran) is flowed at a flow rate of 1 minute per minute at a temperature of 25° C., and 8 samples of the tetrahydrofuran sample solution with a concentration of 0.4 ta r/d are injected and measured. In addition, when measuring the molecular weight of a sample, the measurement conditions are such that the molecular weight distribution of the sample falls within a range where the logarithm of the molecular weight and the count number of a calibration curve prepared using several types of monodisperse polystyrene standard samples are linear. Select. In addition, in this measurement, the reliability of the measurement was determined using the N 706 polystyrene standard sample (Mw = 2
8.8×1 pi, Mn=13.7×1 pi, Mw/Mn=2
．． This can be confirmed by Mw/Mn of 11) being 2.11±0.10. Next, the low polymerization degree polymer and the high polymerization degree polymer in the resin composition of the present invention are both obtained by polymerizing one or more types of the above polymerizable monomers, and The low polymerization degree polymer and the high polymerization degree polymer may be composed of the same kind of monomer or different kinds of monomers.

Among the monomers mentioned above, specific examples of styrenes include styrene, Q-methylstyrene, chlorostyrene, etc., and specific examples of acrylic esters include methyl acrylate, ethyl acrylate, propyl acrylate, and acrylic esters. Specific examples of methacrylate esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, stearyl methacrylate, glycidyl methacrylate, etc. It will be done. Among them, styrene, Q-methylstyrene, butyl acrylate, methyl methacrylate, butyl methacrylate, glycidyl methacrylate and the like are particularly preferred monomers. In addition, in the low polymerization degree polymer and high polymerization degree polymer, in addition to one or more monomers selected from the styrenes, acrylic esters, and methacrylic esters, the object of the present invention can be achieved. Small amounts of other monomers may also be used, such as acrylic acid, methacrylic acid and acrylonitrile.

Although the mixing ratio of the low polymerization degree polymer and the high polymerization degree polymer in the resin composition of the present invention is not particularly determined, the weight of the low polymerization degree polymer 10 having a number average molecular weight of 30,000 or less per part, number average molecular weight 100,000-5
00,000 in a proportion of 5 to 40 parts by weight.

Further, as already mentioned, the resin composition of the present invention has specific values of Mn and Mw/Mn, but also has specific values of Mn and Mw/Mn.
It has a glass transition temperature of 0 to 12,000.

In this way, the low polymerization degree polymer and the high polymerization degree polymer obtained from the above-mentioned specific monomers are uniformly mixed to the extent that they can be obtained through a solution-like mixing state, and Mn and Mw/
A resin composition whose Mn value and glass transition temperature each satisfy the above-mentioned values has excellent crushing properties and heat melting properties, and is extremely useful as a base resin for powder coatings and the like. That is, the resin composition of the present invention is easily crushed;
It is also less likely to be excessively powdered and provides a high yield of powder with a desired fineness range, and more preferably,
When used as a powder coating or a toner for dry electrophotography, it is resistant to breakage due to friction during use and is resistant to becoming excessively fine.

At the same time, the resin composition of the present invention melts at a relatively low temperature during thermal melting, exhibits relatively little decrease in cohesive force even when the temperature rises, and exhibits thermal melting properties that are less affected by temperature changes. It is something. For example, when used as a base resin for powder coatings, even if there is a slight change in temperature, the surface smoothness and adhesion to the adhered material will not deteriorate, and the thickness of the edge portion will not be affected. Furthermore, since the dawning temperature can be selected over a relatively wide range, there is also the advantage that various curing agents can be selected as appropriate. be. Furthermore, when used as a base resin for dry-type electrophotographic toner, beautiful images can be obtained without being affected by the temperature distribution of the fixing section, and the adhesion to paper is also good. Even when the temperature increases, the cohesive force decreases relatively little, so it is used as a base resin for dry type electrophotographic toner for high-speed copying, and the resin does not stick to the heating plate even if it is directly attached to the heating plate. This makes it possible to heat and fix at high speed with high thermal efficiency without causing an offset phenomenon. In addition, in the present invention, it is necessary that the low polymerization degree polymer and the high polymerization degree polymer are mixed uniformly to the extent that they can be obtained through a solution-like mixing state. In order to uniformly mix the two, it is insufficient to thermally melt them and mechanically mix them, and a higher degree of mixing is required. Methods for achieving such uniform mixing include, for example, adding and dissolving both in an appropriate solvent, mixing thoroughly, and then removing the solvent to obtain a mixture; or adding a high polymerization degree polymer to a polymerizable monomer. One method is to dissolve the mixture into a mixed solution and polymerize it using a conventional method, but the latter method is preferable because it can easily achieve more uniform mixing and is advantageous in terms of process. preferable. In such a homogeneous mixture, the high molecular weight segments and low molecular weight segments are mixed together, and the high molecular weight segments prevent the cohesive force from decreasing during hot melting, and the low molecular weight segments As a result, it is thought to exhibit excellent thermal melting properties in that it is melted at a relatively low temperature, but the cohesive force does not decrease much even when the temperature increases. It is believed that by imparting strong balling properties to the product while making the low molecular weight segments more susceptible to crushing, superior crushing properties result.

As mentioned above, the resin composition of the present invention has excellent crushing properties and heat-melting properties, and can be advantageously used as a base resin for powder coatings and dry electrophotographic toners. Not only this, but also useful as hot melt adhesives, various pigment binders, metal coating agents, etc.

Further, depending on the use of the resin composition of the present invention, it may be preferable that the softening point according to the ring and ball method is about 100 to 1700. Next, as for the method of manufacturing the resin composition of the present invention, as described above, a method of dissolving a high polymerization degree polymer in a polymerizable monomer to form a mixed solution and polymerizing this is advantageously adopted. In this case, based on 10 parts by weight of the polymerizable monomer. Number average molecular weight 100,000~
500,000 high polymerization degree polymer is used in an amount of 5 to 40 parts by weight.

In the polymerization, the resin composition obtained by the polymerization has a Mn of 2,000 to 30,000, a Mw/Mn of 3.5 to 40, and a glass transition temperature of 20 to 120 qo. This is what we do. In addition, according to a general polymerization method in which a polymerizable monomer is directly polymerized to form a polymer, Mn can be varied widely depending on the polymerization conditions.
Mw/Mn is usually only 1.5 to 3.0. Therefore, in the polymerization according to the method of the present invention, polymerization initiators commonly used in the polymerization of vinyl monomers, such as lauroyl peroxide, penzoyl peroxide, tert-butyl peroxide, and azobisisobutyronitrile, are used. However, a relatively large amount of the polymerization initiator is used, such as 2 parts or more based on 10 parts by weight of the monomer.

As the polymerization method, ordinary polymerization methods such as bulk polymerization, solution polymerization, and suspension polymerization can be employed.

In the case of bulk polymerization, the polymerizable monomer can be made into a polymer with a low degree of polymerization by polymerizing at a high temperature and increasing the rate of termination reaction. In this method, a mixed solution of a polymerizable monomer and a high polymerization degree polymer can be prepared by adding and dissolving a polymer with a high polymerization degree that has been polymerized in advance into the polymerizable monomer, or by adding and dissolving the polymerizable monomer. There is a method in which a polymer with a high degree of polymerization is contained in the polymerizable monomer by polymerizing - at a low temperature and interrupting the reaction at the initial stage of polymerization. In addition, in the case of solution polymerization, the polymerizable monomer can be made into a polymer with a low degree of polymerization by utilizing chain transfer of radicals by a solvent. Even in this method, in order to prepare a mixed solution of a polymerizable monomer and a high polymerization degree polymer, there is a method of adding a high polymerization degree polymer prepared in advance to a polymerizable monomer solution, There are methods such as polymerizing monomers at low temperatures and interrupting the reaction at the initial stage of polymerization. Next, the suspension polymerization method will be explained. In the present invention, this method is significantly more advantageous than the above two methods. In other words, when using the bulk polymerization method, there is a drawback that the high polymerization degree polymer may be cut due to the tethering force when polymerization is carried out while carrying out the monomer solution, which contains a high polymerization degree polymer and has a high viscosity. In addition, since a solvent is used in the solution polymerization method, various precautions must be taken, and steps of solvent removal and solvent recovery are required.
In the suspension polymerization method, no cutting force is applied, so there is no need to take into consideration the cutting of molecules, and since no solvent is used, problems associated with the use of solvents do not occur. Furthermore, in the suspension polymerization method, the resin composition obtained by polymerization has a pearl-like shape and is easy to separate and wash. In addition, in the suspension polymerization method, in order to prepare a mixed solution of a polymerizable monomer and a high polymerization degree polymer, the high polymerization degree polymer prepared in advance is dissolved in the polymerizable monomer to form a mixed solution. Alternatively, a polymerizable monomer may be added to a suspension system of a polymer in which the polymerizable monomer has been suspended and polymerized, and then mixed to form a monomer solution in which the polymer is dissolved in the monomer. may be in a suspended state. In addition to these methods, various methods for dissolving the highly polymerized polymer in the polymerizable monomer may be employed.

For the reasons mentioned above, it is advantageous to employ the suspension polymerization method in the production method of the present invention, but since the polymerization initiator is used at a high concentration in order to lower the degree of polymerization, The viscosity increases due to the inclusion of polymer in the monomer,
Due to the so-called gel effect, there is a tendency for the temperature of the polymerization system to rise too much during polymerization, but the present inventors have also been able to solve the problems associated with the adoption of such a suspension polymerization method. It is. In other words, by using Q-methylstyrene as a part of the polymerizable monomer, Q-methylstyrene acts as a retarder for the polymerization reaction, suppresses heat generation in the polymerization system, and can normally control the polymerization reaction. . In addition to this, the addition of Q-methylstyrene also has the effect of further reducing the degree of polymerization of the resulting polymer. Therefore, by using Q-methylstyrene as part of the polymerizable monomer and using a relatively large amount of polymerization initiator, it is possible to easily produce a product with a low degree of polymerization. Furthermore, in conventional methods for producing polymers with a low degree of polymerization, mercaptan was used as a chain transfer agent, which left a mercaptan odor in the product, significantly reducing its commercial value. However, according to the above method, such drawbacks can be overcome.

In addition, when the suspension polymerization method is adopted in the method of the present invention, the viscosity of the suspended particles in the initial stage of the polymerization system becomes high due to the high polymerization degree polymer being dissolved in the polymerizable monomer. This contributes to the stability of the suspension system, prevents the migration of monomers into water, prevents the formation of fine powder, and has the unexpected effect of reducing the inclusion of impurities such as suspension stabilizers that adversely affect the product. It can also be effective.

Examples of the present invention will be described below.

Note that hereinafter, parts simply mean parts by weight. Example 1 Polystyreso 1 with a number average molecular weight of 13 x 1 pip was added and dissolved in a mixture of the monomers shown in column A of Table 1 and penzoyl peroxide to form an additive solution, and this was mixed with a partially saponified polyvinyl alcohol product. Resin composition A is obtained by suspending and dispersing .5 parts in 20 parts of water and polymerizing at a polymerization temperature of 80°C to obtain a resin composition A in which a low polymerization degree polymer and a high polymerization degree polymer are uniformly mixed. Obtained.

For comparison, the monomer mixtures shown in columns B and C of Table 1 were polymerized under the same conditions as in the production of resin composition A, without using polystyrene as a high polymerization degree polymer, to obtain a resin. I got B and C. For these, Mn, Mw/
When Mn, glass transition temperature and ring and ball softening point were measured,
It was as shown in Table 1. Table 1 In addition, in order to investigate the thermal melting behavior of these resins, a high-performance flow tester (outlet hole diameter 1 Yanagi, outflow hole length 1 C, plunger pressure 100k9/ground, temperature increase rate 600
/min), the resin composition A and resin B were approximately 100%
It started melting from oo, but it did not start melting with resin C until it reached about 110 qo.

Further, when the change in the melt viscosity of the polymer due to temperature change was investigated, resin composition A showed less change in melt viscosity due to temperature than resins B and C.

That is, although A melted at relatively low temperatures, it retained its "stickiness" even at relatively high temperatures. Furthermore, when pulverization was carried out in a ball mill for two hours, Resins B and C were over-pulverized and showed a wide particle size distribution containing a large amount of characteristic powder, whereas Resin A showed a relatively narrow particle size distribution, especially in the case of characteristic powder. There were few.

Example 2 37.5 parts of styrene, 30 parts of n-butyl acrylate, 7.5 parts of glycidyl methacrylate, and 0.2 parts of penzoyl peroxide are added and mixed into a reactor and polymerized at 80 qo to a polymerization rate of 20%.

Thereafter, it was cooled, and 1 part of styrene, 16 parts of n-butyl acrylate, and 14 parts of glycidyl methacrylate were added thereto to form a mixed solution. The mixed solution contained 15 parts of a highly polymerized polymer with a monomer composition of styrene/n-butyl acrylate/glycidyl methacrylate = 50/40/10 and Mn of 12×1, and styrene 4, n-butyl. Acrylate 4 base, glycidyl methacrylate 2
It consisted of 0 copies. After adding 3 parts of penzoyl peroxide to the mixed solution, 20 parts of toluene at a temperature below the boiling point was continuously added dropwise over 4 hours, and after the addition was completed, the polymerization was completed by maintaining the boiling point for 2 hours. Thereafter, toluene was removed by vacuum drying to obtain a resin composition D in which a low polymerization degree polymer and a high polymerization degree polymer were uniformly mixed.
On the other hand, for comparison, a monomer mixture containing 4 parts of styrene, 4 parts of n-butyl acrylate, 20 parts of chrycidyl methacrylate, and 3.1 parts of penzoyl peroxide was added to 20 parts of toluene in the same manner as above. Dropped, polymerized,
Resin E was obtained.

These resins had Mn of D of 5500 and E of 8000, Mw/Mh' of D of 8.2 and E of 2.4, and glass transition temperature of both D and E of 2300. Next, the resin D
To 100 parts of each of E and E, 3 parts of titanium oxide and 12 parts of sebacic acid were added, and the resulting composition was melt-blended at 12,000 ml and ground in a ball mill for 24 hours. However, the yield of powder with a particle size of 20 to 50 microns, which is suitable for powder coating, was about 80%, whereas when E was used, the particle size distribution was wide and finely pulverized, and the above yield was low. was about 45%.

Furthermore, when these powders were sprinkled on an iron plate and heated at 2000°C, the powder coating using Resin E caused sagging of the resin and uneven thickness at the edges, but resin composition D No such defects were observed in the coatings using this method, and a beautiful coating film with a smooth surface was obtained.

Example 3 4 parts of styrene, 3 parts of methyl methacrylate, 3 parts of n-butyl methacrylate, and 0.17 parts of azobisisobutyronitrile were added to 0 parts of partially saponified polyvinyl alcohol.
．． Add to 20 parts of water containing 5 parts, suspend and disperse,
Polymerization was carried out at 5 qo to obtain a highly polymerized polymer having an Mn of 20×1.

Next, the high polymerization degree polymer 1 pass portion was added and mixed to a mixture of monomers shown in column F of Table 2 and azobisisobutyronitrile to form a mixed solution, and this was mixed with a polyvinyl alcohol partial quencher. Add 20 parts of water containing 0.5 part of the compound, suspend and disperse it, and polymerize at 75°C to obtain a resin composition F in which a low polymerization degree polymer and a high polymerization degree polymer are uniformly mixed. Obtained.

For comparison, Resin G was obtained using the monomers shown in column G of Table 2 in the same manner as above except that the polymer prepared in advance was not used.

Regarding these, Mn, Mw/Mn, glass transition temperature, and ring and ball softening point were measured and the results were as shown in Table 2. Second
10 parts of each of the resins F and G in the table above, 5 parts of Diablack SH (trade name, manufactured by Mitsubishi Kasei Co., Ltd.) and 2.5 parts of Oil Black BW (trade name, manufactured by Orient Chemical Co., Ltd.) were melt-blended and then ball milled. When pulverization was carried out for 5 hours, the average particle size of the powder was 15.2 microns when Resin F was used, and 10.3 microns when Resin G was used.

Further, the yield of powder having a particle size of 10 to 20 microns suitable as a toner for dry electrophotography was about 75% for Resin F and about 35% for Resin G. Also, in the case of resin G, 1
Many fine particles with a diameter smaller than 0 were generated, and particles were likely to become blocked, but in the case of Resin F, no such defects were observed. Furthermore, when the powder of 10 to 20 microns obtained above was used as a toner and fixed at various temperatures of 150 to 20,000, the one using resin G flowed too much at high temperatures, resulting in a decrease in resolution and brightness of the image. However, with the use of Resin F, beautiful images could be obtained in the entire temperature range mentioned above.

Example 4 Toluene below boiling point 20 styrene 8 bases, n
A mixed solution of 2 parts of -butyl acrylate and 5 parts of asobisisobutyronitrile was added dropwise over 5 hours, and the polymerization was completed by keeping the temperature below the boiling point for another 3 hours to obtain a toluene solution of a low polymerization degree polymer. Ta.

This material had Mn of 6200 and Mw/Mn of 2.1. Separately, a mixed solution of 8 parts of styrene, 2 parts of n-butyl acrylate, and 0.2 parts of penzoyl peroxide was suspended and dispersed in 20 parts of water in which 0.5 parts of partially saponified polyvinyl alcohol was dissolved. Polymerization was carried out for 2 hours at midnight to obtain a high polymerization degree polymer. This one has Mn of 14×1 and Mw
/Mn was 2.4. This high polymerization degree polymer 5 part is dissolved in toluene 50, and this solution is mixed with the toluene solution of the low polymerization degree polymer, and the toluene is removed by vacuum drying, and the low polymerization degree polymer and high polymerization A resin composition was obtained in which the polymers were uniformly mixed. This one has Mn of 9
200 Mw/Mn is 13. The glass transition temperature was 6zo○. On the other hand, for comparison, a mixture of 8 parts of styrene, 2 parts of n-butyl acrylate, and 2 parts of penzoyl peroxide was suspended and dispersed in 20 parts of water in which 0.5 parts of partially saponified polyvinyl alcohol was dissolved. , 8000 for one field hour to obtain Comparative Resin 1. This one has Mn of 31
,000, Mw/Mn is 2.2, glass transition temperature is 63
It was ℃. In order to examine the thermal melting behavior of the resin composition and resin 1, 1.5 g of each was placed in a high-pressure flow tester (outflow hole diameter 1 skin, outflow hole length 1 skin, plunger pressure 10k9/ground, When the temperature was increased at a heating rate of 600/min), the resin composition began to flow out from about 105 qo, and the resin composition began to flow out at about 14 qo.
It took until 8 o'clock C to flow out, but Resin 1 started to flow out at 110 qo and completely flowed out at 1420 qo.

Furthermore, when the change in melt viscosity of the polymer with respect to temperature change was investigated, the melt viscosity of the resin composition 1 showed less change with temperature than that of Resin 1.

Claims (1)

[Scope of Claims] 1. A low polymerization degree polymer obtained mainly from one or more monomers selected from styrenes, acrylic esters, and methacrylic esters, and styrenes, acrylic esters, and methacrylic esters. 1 selected from
A resin made by uniformly mixing a polymer with a high degree of polymerization with a number average molecular weight of 100,000 to 500,000 obtained mainly from monomers of at least 1 species to the extent that it can be obtained through a solution-like mixing state. As a composition, the resin composition has a number average molecular weight (Mn) of 2,000 to 30,000, a weight average molecular weight (Mw)/number average molecular weight (Mn) of 3.5 to 40, and a glass transition temperature of A resin composition with excellent crushing properties and heat melting properties, characterized by a temperature of 20 to 120°C. 2 100 parts by weight of a polymerizable monomer mainly composed of one or more monomers selected from styrenes, acrylic esters, and methacrylic esters, and one type selected from styrenes, acrylic esters, and methacrylic esters. By polymerizing a mixed solution with 5 to 40 parts by weight of a high polymerization degree polymer having a number average molecular weight of 100,000 to 500,000 obtained mainly from the above monomers, a low polymerization degree polymer and a high polymerization degree The number average molecular weight (Mn) of the resin composition is 2,000 to 30,000, and the weight average molecular weight (Mw)/number average molecular weight (Mn) is 3. 5 to 40C and a glass transition temperature of 20 to 120C.